Golfdom S PRACTICAL RESEARCH DIGEST FOR TURF MANAGERS TRENDS H P EST I C I D E RE S T R I C T I O N S IN THIS ISSUE

Denitrification Impedes EPA Restrictions on Fertilizer Effectiveness You could lose 20 percent of your applied nitrogen because it was Make Sense lost as a gas 52 By Paul Vincelli Ubiquitous Chlorine Performs Vital Tasks in Turf With this past summer being a high disease-pressure year for cool-season turf- Just because this nutrient isn't in short supply doesn't mean it's grasses in Kentucky and other locations, have been an important tool unimportant 58 for turf managers. Many turf managers are aware that the label for the important contact chlorothalonil includes restrictions added relatively recently. Chlorothalonil is found in OUR SPONSORS such products as Daconil, Echo, Manicure, Chlorostar and Concorde SST.This mater- ial is a low-cost fungicide with broad-spectrum activity, providing partial to complete control of important turfgrass diseases such as dollar spot, brown patch, leaf spot/melt- ing out, gray leaf spot and others. Bayer Environmental Science PAYER! Two restrictions that have particular importance for use patterns for turf disease control are highlighted in this article, with an explanation of the rationale for these www. BayerProCentral. com restrictions. This information is based on the Reregistration Eligibility Decision for 888-842-8020 chlorothalonil published in 1999 by the U.S. Envi- ronmental Protection Agency. This document is an When applied, impressive 337-page, 2-inch thick document that chlorothalonil can describes the scientific basis of EPA's decision to allow reregistration of chlorothalonil, as well as the contaminate surface conditions under which reregistration was permit- ted. Under the 1988 amendment to the Federal Andersons water as a result of GOLF PRODUCTS Insecticide, Fungicide, and Rodenticide Act (FIFRA), drift or application to all registered before Nov. 1,1984, must be www.AndersonsGolfProducts, com 800-225-2639 standing water. reregistered to ensure that they meet current strin- gent standards. The restrictions described below are not limited to certain soil types or turf situations, other than what is outlined in the tables. Fur- thermore, these restrictions cannot be waived by state regulatory agencies. State gov- ernments may take action that is more restrictive than federal action but not less Scotts restrictive. www.scottsco.com Use for home lawns 937-644-7270 Chlorothalonil is no longer labeled for use on home lawns. While this restriction has been in place for several years, it is such an important one that it is worth revisiting. Prior to the institution of this restriction, chlorothalonil was probably the No. 1 jy\coBS=ru fungicide used on residential lawns. This restriction was agreed to by manufacturers of h Textron Company chlorothalonil in order to reduce overall exposure of two populations to the active ingredient: toddlers exposed after the application on home lawns, and residential han- www.jacobsen. com dlers and applicators of chlorothalonil on home lawns. 888-922-TURF Keep in mind that chlorothalonil is registered for disease control on a variety of Continued on page 48 RESTRICTIONS

TABLE 1

Maximum allowable application rates for chlorothalonil Site Maximum individual application rate Maximum seasonal per acre (minimum retreatment interval)* total Golf course greens 11.3 1b ai (14 days) 73 lb ai/A 7.3 lb ai (7 days) Golf course tees 11.3 lb ai (14 days) 52 lb ai/A 7.3 lb ai (7 days) Golf course fairways 11.3 lb ai (one application) 26 lb ai/A 7.3 lb ai (7 days) Sod farms 11.3 lb ai (one application) 26 lb ai/A 7.3 lb ai (7 days) Turf (general) 11.3 lb ai (one application) 26 lb ai/A 7.3 lb ai (7 days)

*Higher application rates require longer intervals between sprays. Lb ai = pounds of active ingredient.

Continued from page 47 An example of how these restrictions apply , including food crops. In order to reduce to a formulated product is provided in Table 2. overall exposure to chlorothalonil in these populations and be in compliance with the Honoring these restrictions Food Quality Protection Act, manufacturers In the real world of day-to-day turf disease man- agreed to voluntarily remove home lawn uses agement, complying with the restrictions out- from the label. lined in Table 1 undoubtedly poses difficulties in some instances. Some turf managers consci- Use restrictions on golf courses entiously follow these restrictions. However, Chlorothalonil may be applied only according to when the health of a putting green, tee or fair- the maximum allowable application rates given way is on the line, a turf manager is under a lot in Table 1 .The restrictions outlined in Table 1 are of pressure to take all available steps to maintain based on ecological concerns regarding aquatic turf health and may even fear for his or her job. ecosystems. When applied, chlorothalonil can Faced with that, the incentive to overlook these contaminate surface water as a result of drift or label restrictions certainly can be powerful. QUICK TIP application to standing water. Its important to understand that these restric- After application, chlorothalonil can move tions are a foundation of EPA's decision to allow One of the most to surface waters in two ways: through runoff as reregistration of chlorothalonil on turfgrasses. Vio- often asked ques- a dissolved chemical and through soil erosion lations of these restrictions not only pose the risks tions concerning as active ingredients are adsorbed to soil parti- described above. Repeated violations also could Roundup Ready cles. Chlorothalonil is highly toxic to various place at risk the registration of chlorothalonil on Creeping aquatic organisms: fish, aquatic invertebrates, turfgrasses. This is an important point. Bentgrass is how it mollusks and shrimp. While living with these restrictions can be can be controlled. I was surprised to learn that a limited number difficult at times, consider the alternative: How This new variety of of fish kills have been documented following much tougher would your job be if the regis- bentgrass is application of chlorothalonil, including applica- tration for chlorothalonil use on turfgrasses tions to turfgrass. Although chlorothalonil is tolerant to Roundup were revoked? EPA did not single out turf- used on many crops, turfgrass uses are consid- grasses. Similar restrictions apply to a long list of only, meaning it can ered to pose a high risk to aquatic ecosystems crops. The good news for turf managers is that be controlled with because of the high application rates used fre- chlorothalonil was reregistered. But you can't other nonselective quently and repeatedly. EPA concluded that assume that it will always remain registered, such as institution of the restrictions outlined in Table 1 particularly if its use is abused. Finale. would bring ecological risks from chlorothalonil Turf managers must experience a great deal of applications down to an acceptable level. Continued on page 50 PESTICIDE RESTRICTIONS

TABLE 2

Maximum allowable application rates for Daconil Ultrex 82.5WDG Maximum individual application rate Amount of product per acre (minimum retreatment interval) per year Site per acre per 1,000 sq ft per acre per 1,000 sq ft Golf course greens 13.6 lb (14 days)* 5.0 oz (14 days)* 88.5 lb 32 oz 8.8 lb (7 days) 3.2 oz (7 days) Golf course tees 13.6 lb (14 days)* 5.0 oz (14 days)* 63 lb 23 oz 8.8 lb (7 days) 3.2 oz (7 days) Golf course fairways 13.6 lb (1 app) 5.0 oz (1 app) 31.5 1b 11.6 oz 8.8 lb (7 days) 3.2 oz (7 days) Sod farms 13.6 lb (1 app) 5.0 oz (1 app) 31.5 1b 11.6 oz 8.8 lb (7 days) 3.2 oz (7 days) Turf (general) 13.6 lb (1 app) 8.8 lb (7 days) 31.5 1b 11.6 oz 5.0 oz (1 app) 3.2 oz (7 days)

*Apply no more than two sprays per growing season at the high rate.

Continued from page 48 because of a love for nature and being outdoors. frustration when restrictions are imposed on pes- Perhaps one can draw on that motivation in those ticides that play an important role in pest man- times when there is a great deal of pressure to agement. You are the people that are directly and overlook these restrictions. I'll never forget the negatively affected by such decisions. It may help glee with which superintendent Mark Wilson ease the frustration to know that EPA did a vast showed me the fish nests in the creek running amount of careful evaluation of the science regard- along Valhalla CC in Louisville, the site of the ing chlorothalonil before making its reregistration 1996 and 2000 PGA Tournament, proving that decision. There was a solid foundation in science golf course development is perfectly at home and in sound, balanced reasoning behind this deci- with environmental protection. I can't imagine a sion, and this has been my general experience with better role model than that. EPA throughout my 15-year career as a professor. It may surprise readers to learn that more Alternatives to chlorothalonil chlorothalonil is used as an antifungal agent in Chlorothalonil has been a widely used fungicide paint than is used on golf courses. This wide- against a broad range of turfgrass diseases. Clear- spread use in such a common product as paint ly, turf managers need to be familiar with products may lead turf managers to mistakenly conclude that can be used as alternatives to chlorothalonil. that the environmental and public-health effects Your state extension turfgrass pathology of chlorothalonil use on turfgrass must be trivial. program probably has a list of fungicides that However, there typically is no significant aquat- may be used against the same turfgrass dis- ic exposure when fresh paint is applied to walls, eases as chlorothalonil. The University of Ken- whereas there is definitely some potential for tucky Extension publication PPA-1, Chemical movement of chlorothalonil into streams, rivers, Control of Turfgrass Diseases, may prove use- and estuaries when applied to turfgrass and other ful. PPA-1 is available on the Web site at crops. Furthermore, toddlers are usually not www. ca.uky. edu/agc/pubs/ppa/ppa 1/ppa 1 pdf exposed to fresh paint (and, in fact, major reduc- PPA-1 should be used only as a starting point tions in chlorothalonil concentration in paint from which you can look into your options have also been mandated by EPA). since products listed there may not be regis- Perhaps understanding the rationale for these tered for use in your particular state. label restrictions will provide encouragement to the turf manager to use alternative products as Vincelli is an extension professor in the depart- ment of pathology at the University of needed. Ask yourself why you got into turf man- Kentucky in Lexington, Ky. agement in the first place. Many times, it's